Do you mean font?
If you have a font file in the correct format then you can simply place it in the Fonts folder and use it. There are several fonts on the StickFonts web site and there is an editor to create your own fonts. See http://ncplot.com/stickfont/stickfont.htm Note some of the fonts are free, as is a simple program to generate gcode. The font editor is not free.